U.S. Department of Agriculture-Agricultural Research Service, Department of Plant Pathology, North Carolina State University, Raleigh 27695, USA.
Phytopathology. 2010 Jul;100(7):719-28. doi: 10.1094/PHYTO-100-7-0719.
Deoxynivalenol (DON) concentrations in mature wheat grain are usually correlated with symptoms produced by Gibberella zeae infection. However, there have been numerous observations of unacceptably high DON in asymptomatic crops, which can lead to lower-than-expected milling reductions in DON. We conducted a field experiment with winter wheat to examine the effect of infection timing and postanthesis moisture on grain quality and DON accumulation. Seven to eight soft red winter wheat cultivars were grown in three successive years in a misted nursery in Kinston, NC. Spikes were randomly selected for individual spray inoculation at 0, 10, or 20 days after anthesis (daa). Starting at anthesis, plots were subjected to 0, 10, 20, or 30 days of mist. Inoculated spikes and noninoculated controls were collected at harvest-ripeness, and the threshed grain was assayed for Fusarium-damaged kernels (FDK) and DON. In 2 of 3 years, percentages of FDK were significantly lower from 10-daa infections than from those at 0 daa, although DON concentrations were the same at the two inoculation timings in 2 of the 3 years. Those results indicate that the period of maximum susceptibility to wheat spike infections by G. zeae is close to or slightly less than 10 daa in North Carolina. In 2 of 3 years, FDK-DON correlation was greater for 0- and 10-daa inoculations and for 0- to 20-daa misted treatments than for the later-inoculated or longer-misted treatments, respectively. The percentage of "low-FDK, high DON" (LFHD) observations (defined as FDK < or = 4.0%, DON > or = 2 microg g(-1)) was higher in 2007 than in 2005 or 2006 (41, 14, and 18%, respectively). In both 2006 and 2007, high percentages of LFHD observations (> or = 60%) occurred under marginal disease conditions involving late infection. We conclude that late infection is an important factor leading to LFHD grain. Periods of rain soon after anthesis likely favor the low-symptom, high-DON scenario, and conditions that create greater within-crop variability of anthesis timing may also be important.
脱氧雪腐镰刀菌烯醇（DON）在成熟小麦籽粒中的浓度通常与玉米赤霉烯酮感染引起的症状有关。然而，有许多观察到无症状作物中 DON 含量过高的情况，这可能导致 DON 的碾磨损失低于预期。我们在北卡罗来纳州金斯顿的一个喷雾苗圃中进行了一项冬小麦田间试验，以研究感染时间和开花后水分对谷物质量和 DON 积累的影响。在连续三年中，7 到 8 种软红冬小麦品种在喷雾苗圃中生长。在开花后 0、10 或 20 天（daa），随机选择小穗进行单独喷雾接种。从开花开始，对 0、10、20 或 30 天的雾进行处理。接种的小穗和未接种的对照在收获成熟时收集，脱粒后的谷物用于检测镰刀菌损伤的籽粒（FDK）和 DON。在三年中的两年中，10-da 感染的 FDK 百分比明显低于 0-da 感染，尽管在三年中的两年中，两个接种时间的 DON 浓度相同。这些结果表明，在北卡罗来纳州，小麦穗部感染玉米赤霉烯酮的最大易感期接近或略短于 10 daa。在三年中的两年中，0-和 10-da 接种以及 0-到 20-da 喷雾处理的 FDK-DON 相关性大于后期接种或更长时间喷雾处理。2007 年的“低 FDK、高 DON”（LFHD）观察比例（定义为 FDK <= 4.0%，DON >= 2 microg g(-1)）高于 2005 年或 2006 年（分别为 41%、14%和 18%）。在 2006 年和 2007 年，在涉及晚期感染的边缘病害条件下，高比例的 LFHD 观察结果（>= 60%）发生。我们得出结论，晚期感染是导致 LFHD 谷物的一个重要因素。开花后不久的降雨期可能有利于低症状、高 DON 的情况，而造成开花期在作物内更大变异性的条件也可能很重要。
